There are a large number of different embodiments of multicoordinate-measuring machines. A survey of the different forms is given in an article by M. Dietsch and H. Lang, published in "Feinwerktechnik und Messtechnik 86" (1978), pages 262 to 269. All the machines described therein are basically of the same construction: the machines consist of three guides which are arranged at right angles to each other and built on top of each other; a probe head is displaceable linearly along each of these guides, and one of three measurement scales is associated with each of the guides.
Coordinate-measuring machines are also known which do not measure in a Cartesian coordinate system but rather in spherical or cylindrical coordinates. Thus, for example, British Patent 1,498,009 describes a coordinate-measuring machine in which the probe head is movably mounted by means of three articulations arranged one behind the other. The position of the probe head in this machine is determined by angle measurements at the respective articulations. A coordinate-measuring machine of similar construction is known from U.S. Pat. No. 4,240,205, wherein the probe head is mounted on a vertically displaceable spindle which, in turn, is guided in a single plane via three articulations which involve vertically oriented axes of rotation. The position of the spindle in the plane is measured by means of a scale and a rotary-angle transmitter.
It is difficult to effect high-precision measurements with these machines since the individual parts of the articulation arm are subjected during a measurement to varying conditions of load, due to the active length of the articulation arm, which depends on the position of the probe head; these mechanisms therefore deform, and the deformation in one axis depends on the positions of the parts of the articulation arm in the other axes.
EP-A-0,342,267 discloses a coordinate-measuring machine in the form of a column which carries a probe head which is vertically displaceable and is movably guided by hand in a plane and can also be rotated around its longitudinal axis. However, it is not readily possible to equip this known machine with drives. In a motorized version which is also described in EP-A-0,342,267, the column is displaceable pursuant to operation of two linearly acting drives in the horizontal coordinates (x) and (y), and the workpiece to be measured is mounted to a rotary table. This machine, however, is not of compact construction, and it is difficult to avoid bending moments in the transmission of y-axis drive forces, which act far outside the center of gravity of the column, to the displaceable column.